Tasers are commonly used by police around the nation as a "non-lethal" weapon to stop confrontation. But their use has been marked with controversy, lawsuits and public scrutiny of law enforcement practices.
Here's a guide to some of the most common questions about police departments' use of Tasers.
How does a Taser work?
Tasers are designed to incapacitate an attacker at a distance; two pronged darts that conduct electricity are fired at a person. Tasers are also equipped to work in a "drive-stun" mode at close range without the use of darts.
Tasers are a specific brand of "electronic control device" – a category of weapon that includes stun guns.
Taser's maker, Axon, says its products work by disrupting the brain's ability to communicate with the rest of the body.
Axon says the darts are designed to work through clothing and do not interfere with a pacemakers.
However, a 2012 article published by the American Hearth Association documented cases where the weapons can stop the heart and lead to death. It advises caution when using the weapon.
A 2017 Reuters report documented more than 1,000 deaths involving Tasers, nearly half of which resulted in a wrongful death lawsuit.
How are police trained to use Tasers?
There is no standardized training for the use of Tasers by police in the United States, but a philosophy determines how police use "less than lethal weapons" like Tasers, said Jim Pasco, the executive director of the National Fraternal Order of Police.
Tasers join other tools like mace and batons – they're designed to "tilt the advantage” back toward an officer in a confrontation, Pasco said.
That's in contrast to guns, according to a 2016 report published by NBC News. Police are trained to "shoot to kill"; a gun's purpose is to stop a confrontation using deadly force.
There are a “fair number of people who committed criminal acts who are alive today because of the availability of less-than-lethal weapons to police officers," Pasco said.
Pasco said that training has generally improved over time as police departments gained experience with device.
In what situations are Tasers most often deployed?
In general, "less than lethal" weapons are used when an officer feels like he or she could be overwhelmed Pasco said.
There's a number of factors that can contribute to this assessment, among them: The age and size of the person involved in the confrontation; how the person is armed; whether that person may be on drugs.
Officers take into account their surroundings too – Pasco said officers are trained to evaluate who around them may be in danger.
NBC News reports some police officers choose to use deadly force over a Taser in potentially dangerous situations because Tasers can be unreliable.
“So many shootings involve an inefficient Taser first,” former Baltimore police Officer Peter Moskos told the network.
The over-use of Tasers has also been criticized. A 2011 Justice Department report cited by Reuters said some officers were overusing stun guns, using them in situations that could be handled without a weapon. It labeled the issue “lazy cop syndrome.”
Can police use a Taser on anyone?
There's no national guidelines on this issue because “it is such a subjective area,” Pasco said.
Reuters reports that some states have passed laws limiting how police can use Tasers. But the publication found that stun gun policies around the country vary widely, differing on such issues as who the weapons can be used on and how many times the weapons can be used.
While there are no definitive national rules on police use of Tasers, there are best practices laid out in a 2011 document funded in part by the Department of Justice.
Among those best practices: The devices "should not generally be used against pregnant women, elderly persons, young children, and visibly frail persons."
In at least one instance, a Federal court has used those best practices to rule on a use of force case, according to NPR.
Contributing: Ashley May, USA TODAY